vintageHIWATTconvention.com

Update:

I added a 20K potentiometer biased the amp to -45
sounds great!!

Thanks Ok so I measured the bias voltage at the 22k resistor it was -39 plate voltage = 480 what would be the next step? I saw a post where someone added a 1meg potentiometer to a 103 circuit. I do have a 1meg potentiometer. However, I saw somewhere else that with the 504 circuit which is what I thi...

thanks

oh here is a picture of the insides it looks all original to me?

SO I just bought custom 5o 1979 combo. It is turret board inside. I checked out this site and there are post about adding a potentiometer for bias for a DR103 circuit. Not sure what circuit is in my amp. Will this work? http://www.vintagehiwattconvention.com/forum/viewtopic.php?f=2&t=1378&hi...

do you know which circuit would apply to my hiwatt
custom 50 1979 combo amp?
Also does any one have an inside picture of the mod?

Thanks

I understand the bias is not adjustable for this amp?
I do work on my own amps is there a mod worth doing to
make the amp adjustable bias without changing the hiwatt sound
or significantly decreasing the value of the amp?

Hi I just purchased a combo 50 watt made in 1979. It is all original with Partridge transformers. Intresting it came with what appear to be the original pre amp tubes all mullard the EL 34 are GE tubes made by Mullard single getter. The amp sounds a lot warmer less harsh than a hiwatt I owned many y...